Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.5.1.3 (dihydrofolate reductase)
 5,819 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The platelet-derived growth factor beta-receptor (PDGFr) is a 180-kDa transmembrane glycoprotein which binds BB-PDGF with high affinity. We have expressed the extracellular region of the receptor in Chinese hamster ovary cells using an expression vector that carries a dihydrofolate reductase gene as an amplifiable marker. Upon amplification of the receptor cDNA sequences by methotrexate a 110-kDa soluble form of the receptor extracellular region (XR) was secreted at 12 mg/liter. The soluble XR protein fully retained the high affinity specific binding of the intact PDGFr for BB-PDGF (apparent dissociation constant, 0.4 nM). In the presence of ligand the soluble XR protein formed complexes that migrated on sodium dodecyl sulfate gels at the size expected for dimers of the protein. When added to fibroblast cultures the soluble XR protein blocked the ability of BB-PDGF to stimulate DNA synthesis but did not alter the mitogenic effect of AA-PDGF. The XR fragment also inhibited the binding of BB-PDGF to PDGFr and the activation of PDGFr tyrosine kinase by BB-PDGF. Thus, the soluble extracellular region protein of the PDGFr binds BB-PDGF with high affinity and functions as a specific antagonist of BB-PDGF actions.
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PMID:A functional soluble extracellular region of the platelet-derived growth factor (PDGF) beta-receptor antagonizes PDGF-stimulated responses. 184 70

A 240-bp DNA fragment encoding a peptide, designated ENV(80), homologous to a conserved part of the gp41 transmembrane glycoprotein of human immunodeficiency virus (HIV) was chemically synthesized and inserted into different plasmid expression vectors. Escherichia coli transformants containing these plasmid constructs produced upon induction high amounts of either an ENV(80) peptide of relative molecular mass (Mr) of 10,000 or the same ENV(80) peptide N-terminally fused to E. coli chloramphenicol acetyltransferase (CAT) or to mouse dihydrofolate reductase (DHFR) having Mr of 36,000 and 31,000 respectively. All polypeptides containing the ENV(80) sequences were strongly reactive with antibodies present in sera from AIDS virus-infected individuals, but not with control sera. The strategy of gene assembly allowed the expression of ENV(80) subfragments fused to DHFR. The serodiagnosis of 15 positive sera by Western blot analysis using these bacterially synthesized ENV(80) subfragments revealed the presence of several immunoreactive epitopes on the 80-amino acid polypeptide which were recognized differently by the various patients.
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PMID:Subregions of a conserved part of the HIV gp41 transmembrane protein are differentially recognized by antibodies of infected individuals. 349 55

Screening tests for antibodies to the human immunodeficiency virus (HIV), based on the indirect ELISA principle using viral preparations as antigen, yield a substantial number of false-positive and false-negative results. These failures are due to the lack of certain viral polypeptides or contaminating cellular polypeptides in viral preparations. Therefore, the accuracy of the screening tests should be improved by using highly purified, synthetic viral antigens. With establishment of such an ELISA antigen in mind, we examined a bacterially synthesized polypeptide [ENV(80)] that corresponds to 80 conserved amino acids of the HIV gp41 transmembrane glycoprotein. ENV(80) was expressed as a DHFR fusion protein in Escherichia coli. Results obtained by HIV ELISA and immunoprecipitation with 497 serum samples from various groups at risk of AIDS were compared with those obtained with the ENV(80) ELISA. The ENV(80) ELISA was found to be superior to the H9/HTLV-III ELISA with respect to sensitivity and specificity and is almost equivalent in accuracy to immunoprecipitation.
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PMID:A new ELISA test for HIV antibodies using a bacterially produced viral env gene product. 354 57